1. The Field of the Invention
The present invention relates to a flexible or foldable panel for a seat such as a chair or a stool. In particular, although not exclusively, the invention relates to a flexible panel for a reclinable office chair. The invention also relates to a seat depth adjustment mechanism. While the invention is described in terms of commercial office chairs, the invention may have application to any other type of seating such as public seating for theatres, aircraft or domestic seating.
2. The Relevant Technology
When a person sits in a chair, there are two boney protuberances on which the person sits. These are referred to as the ischial protuberositises. It can be uncomfortable to sit on these for a period of time and therefore seats such as chairs and stools are generally padded with one or more layers of foam for user comfort. Depending upon the quality of the foam, the user can still experience some discomfort after a period of time because once he sinks down into the foam, he still may encounter a greater resistance bearing on the ischial protuberosities, compared to other parts of his derriere.
It is an object of at least an aspect of the present invention to provide a flexible seat panel which more comfortably accommodates the occupant's ischial protuberosities.
In office chairs, it is desirable to have seat portions in which the forward portion is deflectable under the weight of the occupant. See for example U.S. Pat. Nos. 5,050,931 and 4,498,702. U.S. Pat. No. 5,050,931 has a generally flexible seat portion but a relatively complex spring mechanism is required in order to upwardly bias the forward portion and prevent it from unduly sagging under the occupant's weight. The arrangement shown in U.S. Pat. No. 4,498,702 is a cumbersome arrangement in which a separate forward portion of the seat portion is connected to a rearward portion of the seat portion by leaf springs. The prior art suffers from the disadvantage that in order for the seat portion to have sufficient strength, complex spring mechanisms are required to prevent the forward portion from unduly sagging under the weight of the occupant.
It is yet another object of at least an aspect of the present invention to provide a flexible or foldable seat panel which alleviates the requirement for a complex spring mechanism to resist undue sagging of the forward portion of the seat portion.
As the reader will appreciate, people come in a great deal of different shapes and sizes. As the chair market stands at present, office chairs are required to cater for a large range of occupant sizes. A commonly available adjustment is seat depth adjustment as illustrated in U.S. Pat. No. 5,871,258. This US patent also illustrates that the forward portion of the seat portion may be deflectable under the occupant's weight thereby defining a transverse fold line. However, the fold line is disposed the same distance from the front of the seat portion, irrespective of the seat depth position which does not cater for different sizes of seat occupants. Furthermore, another disadvantage of this prior art arrangement is that a complex spring arrangement is required to upwardly bias the forward portion of the seat portion. In one embodiment, the user is required to adjust the spring force to suit his requirements and in another embodiment the spring force is non-adjustable.
It is therefore an object of at least an aspect of the present invention to provide a means for resisting flex of the forward portion of the seat portion which offers a resistance correlating to the seat depth position.